A quartz crystal vibrator of the tuning fork type having a frequency of 32,768Hz is generally used for electronic time pieces. This frequency is decided by the present level of conventional IC-technique. The tuning fork vibrator is selected because of the ease of supporting a tuning fork vibrator by it's stem without lowering the quality of the vibrator.
However as calculated threoretically a vibrator of the tuning fork type has a frequency-temperature characteristic which is approximately a parabolic curve and the parabolic coefficient of the vibrator is large. It is therefore difficult to provide a high accuracy quartz crystal wristwatch. In order to provide a high accuracy quartz crystal wristwatch it is necessary to improve the frequency-temperature characteristic of the vibrator and it is then difficult to make AT cut quartz crystal vibrator of a small size which has a good frequency-temperature characteristic. It is therefore impossible at present to use it in a wristwatch. The development of SOS-IC is well advanced but it is of no practical use in a wristwatch.
A tuning fork type quartz crystal vibrator is generally supported by the stem portion which is ridgedly secured to a support member. When the vibrator is subjected to shock the displacement of the tines of the vibrator is very large and therefore the tines of the vibrator may chip off.